We resolve the long-standing controversy regarding far-field imaging by a planar lens made of a left-handed medium and demonstrate theoretically that the far-field image has a fundamentally different origin depending on the relationship between losses inside the lens and the wavelength of the light, $\lambda$. At small enough $\lambda$, the image is always governed by diffraction theory, and the resolution is independent of the absorption if both $\mathrm{Im}ϵ⪡1$ and $\mathrm{Im}\mu ⪡1$. For any finite $\lambda$, however, a critical absorption exists below which the superresolution regime occurs, although this absorption is extremely low and can hardly be achieved. We demonstrate that the transition between the diffraction-limited and superresolution regimes is governed by a universal parameter combining absorption, wavelength, and lens thickness. Finally, we show that this parameter is related to the resonant excitation of surface plasma waves.

• Received 22 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.205102